The complete cervical series of the morphologically similar and possibly closely related brachiosaurid Giraffatitan Paul, 1988 is known, and consists of 13 cervicals measuring 8.5 m. The Sauroposeidon cervicals are on average 37% longer than the corresponding vertebrae of Giraffatitan, suggesting a complete neck length of about 11.5 m. If Sauroposeidon is a basal somphospondyl rather than a brachiosaurid, as suggested by D’Emic & Foreman (2012), then a more apposite comparison might be to Euhelopus, which had 17 cervicals. In extant lizards and crocodilians, as in basal archosaurs (Fig. Characteristic of diplodocids, this primitive, four-legged, plant-eater had a long, whip-like tail. It may be that these taxa retained their epaxial tension members primarily on the midline, in the intermetapophyseal trough, while diplodocids shifted theirs laterally; but we know from osteological evidence (see above) that at least some diplodocids did have ligaments or muscles anchored within the trough. 9.1; Schwarz, Frey & Meyer, 2007, figure 6E). Reasoning by analogy with modern giraffes, most paleontologists believe sauropods evolved their ultra-long necks in order to reach high leaves. However, the head length of sperm whales is positively allometric and increases with age even in adults (Cranford, 1999, p. 1141 and figure 4), so a 20-m adult might well have a head slightly more than 7 m long. Unpublished MSc Thesis, University College London, London, UK, Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen, Journal of Experimental Zoology (Mol Dev Evol), Physeter macrocephalus. Marine Fisheries Review, Comparative Biochemistry and Physiology Part A, Maryland Geological Survey, Lower Cretaceous, Bulletin of Gunma Museum of Natural History, Transactions of the Zoological Society of London, Scientific Reports of the Whales Research Institute, Tokyo, Memorie della Società Italiana di Scienze Naturali e del Museo Civico di Storia Naturale di Milano, Revista del Museo Argentino dei Ciencias Naturales, Nuevo Serie, Society of Vertebrate Paleontology Memoir, Bulletin of the American Museum of Natural History, Memoirs of the American Museum of Natural History, New Series, Bulletin of the Peabody Museum of Natural History. These lengths are 3.60, 4.04 and 4.06 times the lengths of their respective C5s. In many clades, they were further lightened by reduced dentition, because unlike other large-bodied animals such as hadrosaurs, ceratopsians and elephants, sauropods did not orally process their food. Another giant theropod, Gigantoraptor erlianensis Xu et al., 2007 belongs to another long-necked group, Oviraptorosauria. Due to its immense size, it would have probably been a high-level browser, meaning it would not have to compete with lower-level browsers such as Stegosaurs or smaller Sauropods. However, in one clade – birds – an elongate trachea is not unusual, having evolved in swans (Banko, 1960), cranes (Johnsgard, 1983), moas (Worthy & Holdaway, 2002), birds-of-paradise (Frith, 1994) and several other groups. Finally, it should be noted that both of the long-necked theropods discussed above are known from incomplete remains that do not include any informative cervical material. In many long-necked animals, the legs are of a similar length and so the neck elongation can be explained as a simple consequence of the need to reach down to ground level – for example in order to drink. One of the best-known sauropods, Diplodocus was a large long-necked four-legged animal, with a long, whip-like tail. On the other hand, many basal sauropods had ASPs of 0.30–0.40 and therefore SG of 1.1–1.4. With the exceptions of sloths and sirenians, mammals are all limited to exactly seven cervicals due to developmental constraints: mutations to the Hox genes that control the number of cervicals also give rise to neonatal cancer and other birth defects (Galis, 1999; Galis & Metz, 2003). While the impact of soft-tissue diverticula is more difficult to assess, it is easy to imagine that the density of a typical neosauropod neck may have been less than 0.5 kg/dm3. Note: You are now also subscribed to the subject areas of this publication Other groups of large-bodied animals have not evolved long necks, instead either developing large heads on short necks (ceratopsians, proboscideans, tyrannosaurs) or a compromise of a medium-sized head on a medium-length neck (hadrosaurs, indricotheres). Although pneumaticity was undoubtedly an important adaptation for increasing the length of the neck without greatly increasing its mass, a longer neck remains more mechanically demanding than a shorter neck of the same mass, because that mass acts further from the fulcrum of the cervicodorsal joint, increasing the moment that must be counteracted by the epaxial tension members. Because sauropods were so much bigger than their relatives, and their necks so much longer, mechanical considerations in the construction of their necks were significantly more important than in their outgroups. PeerJ promises to address all issues as quickly and professionally as possible. Fossil findings also confirm that the massive, pillar-like legs and skeletal construction were able to support the giant sauropods on land. The largest sperm whales are up to 20 m in total body length (Gosho, Rice & Breiwick, 1984), which would give a head length of 7 m if these largest individuals scaled isometrically with the 16-m whales. Heavy quadrupedal animals don’t need long tails for balance, nor do they need long necks for balancing long tails (don’t take this the wrong way, but you come across as almost implying that sauropods just randomly evolved big tails for no apparent reason). Interpretation of sauropods as living animals is made especially difficult by the lack of good extant analogues. Reviewing the characters that facilitate the evolution of extremely long necks, it is apparent that only sauropods have them all (Table 3). If they were omnivorous, for example, then their use of more nutritious food may have mitigated the need for increased feeding envelopes. And while that might seem a little strange, it makes more sense when you understand the environment that Diplodocus lived in. As a macronarian, it had a long neck and larger forelimbs than hind limbs. The dinosaur's tooth had thick enamel to enable the animal to feed on tough conifer leaves. This paper has been reviewed by at least eight referees at various times. "Moreover we found that the enamel of the teeth of Bagualia was about 7 times thicker than those of the other herbivores that went extinct. Multiplication of cervical vertebrae obviously contributes to neck elongation. Dashed arrows indicate muscle passing medially behind bone. The long-necked theropods may not have been under the same selection pressure to evolve long necks as were sauropods. C. M. flexor colli lateralis. Some speculation exists as to whether it may have had a defensive or noisemaking (by cracking it like a coachwhip) function. Also, longer trachea and blood vessels cause physiological difficulties: weight support is only one of the problems imposed by a long neck. Huge long-necked sauropod dinosaurs had 'zigzagging' bones that fit together like pieces of a jigsaw puzzle to help support their large bodies, research from the University of Michigan revealed. In some sauropods, including Erketu and Mamenchisaurus, which were proportionally long-necked even by sauropod standards, the neural spines are strikingly low, and the epipophyses no higher – a surprising arrangement, as low spines would have reduced the lever arm with which the epaxial tension members worked. The osteology of the cervical vertebrae makes mechanical sense; the major muscle insertions are prominent osteological features located at the four “corners” of the vertebrae (Fig. Sauropod heads were simple cropping devices with a brain and sense organs, and did not require special equipment for obtaining food, such as the long beaks of azhdarchids (Chure et al., 2010, pp. MP Witton (University of Portsmouth) provided helpful discussion on pterosaur necks. Ossified tendons in the lower limbs of birds are typically found distal to the knee (Hutchinson, 2002, p. 1071), where the tendons are constrained to be long and thin by the overall construction of the limb; ossification may be the only viable way for birds to advantageously shift the mechanical properties of these tendons. As a macronarian, it had a long neck and larger forelimbs than hind limbs. While it could reach up to eighty feet in length, most of that length was accomplished via its long neck and whip-like tail. Air Space Proportion (ASP) of sections through sauropod vertebrae. Its forelimbs were slightly shorter than its hind limbs, resulting in a largely horizontal posture. Exceptionally long necks evolved in at least four distinct sauropod lineages (Fig. 5 and 6) indicate that in at least one specimen the vertebral column is complete. The complete skeleton PIMUZ T 2818 has a total length of 420 cm (Nosotti, 2007, p. 8), of which the neck accounts for 211.2 cm (Tschanz, 1988, p. 1003) – almost exactly half. Almost all dinosaurs had long tails and some also had long necks.. One maverick paleontologist has even suggested that the necks of some … Dicraeosaurids (Dicraeosaurus, Amargasaurus, and related taxa) had reduced postcranial pneumaticity compared to other neosauropods, both in terms of the number of presacral vertebrae that were pneumatized, and in the air space proportion (Schwarz & Fritsch, 2006). However, some aspects of muscle insertion in sauropod necks are mysterious and may be illuminated by closer comparisons to their extant relatives. 1 and 2). It is tempting to imagine an evolutionary pathway in which bifurcation of neural spines was an intermediate step in the evolutionary shift of the insertions of the large multisegment epaxial muscles from the neural spine to the epipophyses. Diplodocus specie… These reptiles were the largest of all dinosaurs and the largest land animals that ever lived. Even in Camarasaurus lewisi BYU 9047, in which every postaxial cervical vertebra is at least partially bifid (McIntosh et al., 1996b), the bifurcation is very slight in the anterior cervicals and probably of little mechanical consequence. 11.4, where a small neural spine remains in the cervical of Majungasaurus, but is dominated by epipophyses. Bulletin of the Geological Society of China, Institute of Vertebrate Paleontology and Paleoanthropology Monograph, Series I, Biochemistry, Biophysics and Molecular Biology, PeerJ (Life, Biological, Environmental and Health Sciences), PeerJ - General bio (stats, legal, policy, edu), Buffetaut, Grigorescu & Csiki, 2002, p. 183, Kubo, Mitchell & Henderson (2012, p. 570), Zweers, Vanden Berge & Koppendraier, 1987, van der Leeuw, Bout & Zweers, 2001, figure 5, Mechanics of posture and gait of some large dinosaurs, Scientific news: 5. These observations enable us to draw conclusions about sauropod neck soft tissue beyond what the extant phylogenetic bracket would allow. The specific gravity (SG) of compact bone is 1.8–2.0 in most tetrapods (Spector, 1956), so an element with an ASP of 0.60 (and therefore a compact bone proportion of 0.40) would have an in-vivo SG of 0.7–0.8. The long-necked, long-tailed animal with four sturdy legs has been mechanically compared with a suspension bridge. Giant animals also produce a lot of body heat, and other studies have suggested that their long neck could dissipate body heat -- a bit like the big ears of modern elephants, Pol explained. In fact, Diplodocus is the longest dinosaur known from a complete skeleton. Notes on the Paleontological Laboratory of the United States Geological Survey under Professor Marsh, Paleontology and biostratigraphy of Mongolia. 11.2), the muscles of the neural spine were presumably significant, and would have acted primarily along the midline of the neck. Some of the other long-necked taxa listed in Table 3 seem to have been better equipped to evolve longer necks. If bifid spines conferred a great advantage, they would presumably be found throughout the neck – although the importance of stability, and the difficulty of attaining it, is greater in the posterior part of the neck, which bears greater forces than the anterior part. In this respect, sauropod osteology is intermediate between the conditions of crocodilians and birds – so the widely recognized similarity of sauropod cervicals to those of birds (e.g., Wedel & Sanders, 2002; Tsuihiji, 2004), while significant, should not be accepted unreservedly. 11). This is particularly clear in Fig. Short neural spines do not indicate poor mechanical advantage for these muscles, because they act at high angles of inclination to the long axis of each vertebra. Bifid presacral vertebrae of sauropods showing ligament scars and pneumatic foramina in the intermetapophyseal trough. 1 and 2; and “kei” and Kevin Ryder for permission to use their photographs. Note that most of the length estimates in this section are necessarily imprecise, being based on incomplete specimens and cross-scaling assumptions. Its great size may have been a deterrent to the predators Allosaurus and Ceratosaurus: their remains have been found in the same strata, which suggests that they coexisted with Diplodocus. Diplodocids are common in the Late Jurassic in North America and East Africa, but this dinosaur is the only one found in … Even if this were so, however, it is difficult to see the benefit in Apatosaurus excelsus Marsh, 1879a of cervical ribs held so far below the centrum – an arrangement that seems to make little sense from any mechanical perspective, and may have to be written off as an inexplicable consequence of sexual selection or species recognition. In light of the demanding mechanical constraints that were imposed on sauropods, it is surprising that their necks vary so much morphologically, with different lineages having evolved dramatically different solutions to the problem of neck elongation and elevation. Second, although bone is much stiffer than tendon, it is actually not as strong in tension, so that an ossified tendon is more likely to break under load. Bagualia alba would likely have been 10 tons -- around the size of two African elephants -- but later sauropods were up to 40 meters in length and … H. Muscles inserting on the ansa costotransversaria (“cervical rib loop”), shown in brown. Ouvrage enrichi de figures en taille-douce, The role of phylogenetic analysis in the inference of unpreserved attributes of extinct taxa, A new giant pterosaur with a robust skull from the latest Cretaceous of Romania, The first giant dinosaurs: a large sauropod from the Late Triassic of Thailand, Winning by a neck: tall giraffes avoid competing with shorter browsers, Biggest of the big: a critical re-evaluation of the mega-sauropod, First complete sauropod dinosaur skull from the Cretaceous of the Americas and the evolution of sauropod dentition, Two new oviraptorids (Theropoda: Oviraptorosauria), Upper Cretaceous Djadokhta Formation, Ukhaa Tolgod, Mongolia, Proceedings of the Academy of Natural Sciences of Philadelphia, On a gigantic saurian from the Dakota epoch of Colorado, Geology and paleontology: a new species of. "The only ones that survived this crisis were eusauropods. Epipophyses are found in most, though not all, sauropods and theropods. Unilateral branch stripping is the most likely feeding behavior of Diplodocus, as it explains the unusual wear patterns of the teeth (coming from tooth–food contact). Ossification of the hypaxial tendons into long cervical ribs may have provided several benefits for sauropods: Long tendons move the bulk of the hypaxial neck muscles closer to the base of the neck, which reduces the lever arm of the neck mass. These trees supplanted the lush vegetation of the humid environment that preceded the volcanic event. This disparity is particularly evident in the cervical vertebrae (Fig. Specifically: A. M. longus colli dorsalis. For example, Sauroposeidon has ASP values up to 0.89 and therefore SG as low as 0.2 in some parts of its vertebrae. Diplodocus is … Whatever the advantages of bifid spines, they were clearly not indispensable, as some sauropod lineages evolved very long necks with unsplit spines (e.g., brachiosaurids, Sauroposeidon, and most titanosaurs, including the very long-necked Puertasaurus). Within Theropoda, at least three lineages evolved especially long necks. It is possible that neck length was positively allometric in these clades, as in sauropods, and they may have had necks somewhat longer than isometric scaling suggests. What's more, some sauropods walked on two legs while others used four. Figure 10 shows the cervical skeleton of Euhelopus as it actually is, and reconstructed with speculative muscle attachments that would have been more mechanically efficient: why did sauropod necks not evolve this way? However, whales provide an example suggesting it is unlikely that the evolution of long necks in terrestrial mammals has been limited by tracheal dead space. It is impressive that the azhdarchid pterosaurs seem likely to have achieved 3m while retaining flight: no doubt their pneumaticity was a key feature in making this possible in spite of their large heads. Birds are phylogenetically closer to sauropods, and some birds (e.g., swans and ostriches) have proportionally very long necks. Why were extinct gigantic birds so small? All sauropods had a very long, muscular tail, a massive body, and four sturdy, columnar legs that ended in elephant-like feet. But other long-necked groups are more limited in their elongation of individual vertebrae. As is frequently the case with sauropods, no skull has yet been found. This is a consequence of scaling, which makes it impossible for sauropod necks to be similar to those of ostriches. In birds, this muscle originates from the processes carotici, which are absent in the vertebrae of sauropods. Applying a similar scaling relationship to Sauroposeidon, and conservatively assuming that the largest available vertebra was the longest in the neck, yields an estimated neck length of 16.5 m. We will not know which of the two estimates is more accurate until more articulated cervical material of Sauroposeidon comes to light. However, this raises as many questions as it answers since pumping blood to a height of 30 or 40 feet would strain even the biggest, most robust heart. This, however, would raise the question of why other taxa with bifid spines (e.g., Camarasaurus) also retained elongate cervical ribs, and in the case of Mamenchisaurus apparently evolved apomorphically long cervical ribs (Russell & Zheng, 1993, pp. We longus colli dorsalis would have had the dual function of support and lateral motion. Their spine was hollowed out at the sides, providing structural strength while remaining relatively lightweight. Using this ratio to estimate the C1–2 lengths for each specimen, we find by adding the lengths of the individual cervicals that the three specimens had necks measuring approximately 511, 339 and 398 mm. But these low spines would have reduced the lever arm with which epaxial tension members acted. The lightest postcranial bones for which data are available are those of Sauroposeidon and some pterosaurs. The sauropods were quadrupeds, meaning that they traveled on all four legs. Structure and relationships of opisthocoelian dinosaurs. This trend reaches its peak in the trumpet manucode Phonygammus keraudrrenii (Clench, 1978). But as noted above, sauropod vertebrae were very pneumatic, typically consisting of 60% air. In birds, the largest and mechanically most important epaxial muscles (M. longus colli dorsalis and M. cervicalis ascendens) insert on the epipophyses of the cervical vertebrae – that is, distinct dorsally projecting tubercles above the postzygapophyses. … In extinct animals, except in a very few cases of exceptional preservation, only the fossilized bones are available: but using extant animals as guides, osteological features can be interpreted as correlates of the absent soft tissue, so that the ligaments and musculature of the extinct animal can be tentatively reconstructed (Bryant & Russell, 1992; Witmer, 1995). If this is correct, then its neck was subject to a quite different biomechanical regime than those of sauropods. The long-necked, long-tailed animal with four sturdy legs has been mechanically compared with a suspension bridge. The sauropods are some of the most iconic prehistoric vertebrates. Due to its immense size, it would have probably been a high-level browser, meaning it would not have to compete with lower-level browsers such as Stegosaurs or smaller Sauropods. (In the caption to Wedel (2003, figure 2), from which Fig. Reduced tendon elasticity is known to improve position control of the involved muscles (Alexander, 2002, p. 1009). If it were similarly proportioned to PIMUZ T 2818, its neck would have measured 269 cm. More direct evidence is found in ligament scars in the troughs of some diplodocids: these can be prominent, as in the doorknob-sized attachment site in the Apatosaurus sp. It is significant that all other clades of large (>10 ton) terrestrial herbivores – ceratopsians, hadrosaurs, proboscideans, and indricotheres – practiced extensive oral processing of their food, requiring massive dentition and correspondingly large heads. Our promise The first two of these features were inherited from a common saurischian ancestor. Had they not died out at the end of the Cretaceous, they might have gone on to attain larger size. The research was published in the journal Proceedings of the Royal Society B on Tuesday. They have long been regarded as bulk feeders, with teeth and jaws that were able to cut and swallow all kinds of plants including conifers. 388–389). A similar degree of elongation is approached by the ostrich, in which C12 can attain an EI of 4.4 (measured from Mivart, 1874, figure 29), and by the giraffe, in which the axis can attain an EI of 4.71 (personal measurement of FMNH 34426). Larger compared to the very end of the Cretaceous, two of these features would have greatly the. Titanosaur for which cervical material has been described on your preferences swans and ostriches ) have very. Warmer, more arid environment et, Tue November 17, 2020 the...., the muscles inserting on the physiological implications of neck elongation in ;! 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